Pollution in Marine Urban Ecosystems
The term 'pollution', contrary to the popular conception that is often focused on macro pollution (plastics and trash), describes a vast array of factors that can have perturbating consequences on living organisms. Basically, anything that is too abundant compared to what is considered normal/optimal is pollution. In Marine Urban Ecosystems (MUE), pollution can be of multiple sources and nature. Macropollutants like plastics and other waste are the most visible for the untrained eye and can be more or less abundant near cities and especially beaches (please don't litter). Urban areas can, however, exert other stresses that can have impacts that are orders of magnitude more important than plastic etc.
Most notably Chemical Pollutants like heavy metals have been shown to exert high toxicity towards the ecosystem. Cadmium, Lead, Copper, Quicksilver are produced in minuscule amounts by diverse human activities but accumulate in the environment. Persistent organic pollutants are produced in a similar manner. Wastewater conveys these chemical pollutants towards the sea where they most often accumulate in the food chain and the sediments. This accumulation concentrates the pollutants in living beings where they can harm the organism.
Biological pollution is considered equally harmful and occurs when a species spreads and reproduces without control, harming the ecosystem. Most often Non-Indigenious Species are considered as biological pollution, but local species can also contribute if they are considered harmful. The disturbed nature or MUEs favours species that use quick growth rates and high reproduction rates with a short lifecycle, which highly advantages species that are likely to become biological pollutants.
More recently, other pollutions gained the attention of the scientific community. Marine Noise and Artificial Light at Night (ALAN) are a recent focus of research and seem to influence the local fauna and flora. Here the effects are more subtle than previously mentioned pollutions but are more difficult to quantify since they mostly influence the behaviour of marine organisms.
The effects of pollution in a certain area are difficult to predict. Many organisms have adapted to cope with a high amount of any kind of pollution in MUEs. The resulting ecosystems constitute environments that are vastly different from natural ecosystems and harbour their own species with new behaviour and interactions. It is making me a little bit sad seeing a fish housing in a plastic pot on the bottom of a harbour (Picture) but I can't help but wonder how the fish sees its strange home.